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3D-Based CAPTCHAs Become a Reality
mateuscb writes "A new way of creating a CAPTCHA using 3D objects has become a reality. The idea was thought up independently by blogger Taylor Hayward and by the folks at YUNiTi.com. 'Similar to Hayward's idea, this new technology relies on our ability to identify objects in 3D instead of using alphanumeric characters. YUNiti's 3D Captcha, however, has three objects in the challenge and extends the list of images to any object, not limiting it to animals as in Hayward's idea. This increases the challenge's level of complication to prevent computers from successfully making the correct guesses.' I, for one, welcome the thought of not having to read more and more complex CAPTCHA. Lately, I've been having a hard time getting CAPTCHA to work the first time."
I want 4D CAPTCHAs, so even humans can't figure them out. Think... Hypercube... the CAPTCHA.
I've been having a hard time getting CAPTCHA to work the first time.
And the secondtime . And the third time. And the fourth. And the....
Let's see now. If the spammers and robot makers went outside, done something worthwhile and produced something the world badly needs (food) then this nonsense wouldn't exist, I could surf in peace and the starving millions would live a little longer. The very existence of CAPTCHA's proves the human race is badly in need of a reset.
Interesting, but in a previous /. discussion, I got convinced that there was no perfect captcha, since one can simply pay a group of underpaid workers (e.g. in poor country) to manually solve the captchas...
Animoog.org
I dunno, there has been quite a bit of research done with image/object recognition. You could break this by not matching pictures directly but by seeing that the first one is a bunny (so look for a bunny in the list), the second one is a hammer, etc...
CAPTCHAs are among the best motivators for progress in AI research since DARPA began throwing gobs of money around. The question is, what will happen to online forums and social/financial networks when machines become indistinguishable from humans?
As is, this seems relatively easy to defeat and well within reach of available technology. The number of 3D models is rather low and they have a very clear silhouette and also a very distinct one for each models. So all one has to do is to search for the best matching silhouette.
The good thing however is that 3d models have enough flexibility so that one could conquer many attacks, adding background images and texture would make it much more difficult to get a clear silhouette and one could of course easily introduce many more models into the mix.
Would that be innovative?
Or as an alternative, we could actually track down the people who continue to make the Internet a swamp, beat them within an inch of their lives, let them spend a hot humid summer in full body traction, and maybe not only wouldn't they do it again but others might not either.
And put it on YouTube afterwards.
"It's the height of ridiculousness to say for those 9 lines you get hundreds of millions."
The problem with 3d images, and complex non text CAPTCHAs in general is image size. You need to have enough different images so that the computer can't just brute force it, and those images need to be big enough so the user can actually see it. by the time you fulfil these obligations the CAPTCHA is taking up a good 3/4 of a page.
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If you wanna post on my site, you better be prepared to solve the 5D hyper-hyper-cube!
It's becoming more evident every day that the first cylon will be a Captcha solver.
It won't be too long before Captchas will be little reading comprehension tests like on a 3rd grade social studies test.
After that we'll just have to revert to empathic testing. Sadly those with Autistic Spectrum Disorders will no longer be able to use webmail.
Everyone has a great idea for a CAPTCHA, but very few people know what the hell is really going on. Remember that the machine doesn't need to solve the CAPTCHA every time, that machines are infinitely patient and have huge memories, and that another machine needs to make sure the human gave the right answer!
Ideas that won't work:
Really, it's very easy to think you've come up with a very clever CAPTCHA. When you think that, all you've done is stoked your ego and screwed yourself over. It's the same reason why we don't roll our own cryptography: CAPTCHA-making is a very hard problem, mainly because your problem space must be infinite (to avoid an attacking machine simply memorizing answers), the answers verifiable by a machine, but the problems not solvable by a machine.
How many questions can be checked by machines but not answered by them?
Not many; fewer every day. There are no questions that can't be answered by a computer (and which can be answered by a human mind). The Church-Turing thesis has some validity: the human mind is no more powerful than a turing machine, and ultimately, computers and our brains are equivalently computationally. There's nothing a computer can't solve: there are just things we haven't figured out yet.
Oh, and there are problems computers can't (easily) solve, but can verify. The problem is that human brains can't solve these problems either!
Before someone jumps in with "humans can solve the halting problem!" -- we really can't. There are problems that obviously halt, and programs that obviously don't. We can tell these apart, but so can computers. It's the complicated, borderline cases that trip up both people and computers.
Furthermore, there are important caveats to the halting problem: first, you can tell whether a program halts in a given time. You just run it and see whether it halts! Human beings do this all the time when debugging hanging programs. We use a good heuristic that says "if a program doesn't quit after a good long while, it probably won't quit at all." (And that holds in most cases.)
Second, the halting problem can be solved, via brute force if necessary, for a restricted-memory machine. Make the available memory size small enough and you can actually perform useful validation. The proof of the halting problems' unsolvability applies only to unrestricted turing machines.
A true turing machine has never been built, and can't exist in our universe. Every computer is a limited-memory approximation.
It's worse than that, actually. Remember, a machine doesn't need to pass the captcha every time. You only need to worry about re-training your image recognizer when the success rate falls below a useful level, and even very low levels of CAPTCHA success are useful for spammers.
Won't work. Where will you get your pictures of Siamese Cats? If you take them yourself, you'll only have a few. Spammers will simply train their bots to recognize these cats.
If you have lots of pictures of cat and non-cat objects, the attacker has two strategies: either he can get the same database you did (which you didn't make, because making a large enough database would be cost-prohibitive), or failing that, he just trains his image recognized to pick out characteristics of Siamese cats the same way a human brain would.
You know enough that recognizing 3D shapes is a solved problem; doesn't it seem clear that recognizing textures would be just as tractable?
And I imagine you could create tough cases, but these cases will also trip up human beings.
It appears you overcame that obstacle
3D recognition is a solveable problem. As someone else mentioned, there are machine learning techniques that work. Recognizing a 3D object from multiple angles is a very old AI problem, one that DoD-funded work was addressing as early as the 1960s. It's easier than 3D reconstruction from multiple 2D images, which is a commercially available technology.
I think we're reaching the end of the line on CAPCHAs. There's now overlap between the smarter vision programs and the dumber users.
So Jagex's Runescape MMORPG has had this for a couple of years in random events to defeat macros.
http://www.runescape.com/